does not have authorization to perform action 'Microsoft.Network/loadBalancers/read

[JohnnyPalmer-AMI]

If I run the code I get the above error.
To me it looks as though your example expects a load balancer

resource loadBalancer 'Microsoft.Network/loadBalancers@2021-05-01' existing = {

to be already set up, do you have an example where it creates the load balancer on the fly or am i missing something ?
(I have read that granting permissions will fixes the error above, however do i have to have an existing load balancer already set up to use this example)

[sebafo]

The loadbalancer is created by the Container Apps environment automatically. There should be a new resource group named like your generated DNS name for the Container Apps environment. (something like MC_GENERATED_NAME-rg_GENERATED_NAME_LOCATION)
Does your user have access to this newly created resource group in your subscription? This is required to read the IP address of the LB to create the Private Link Service for the LB.